bisect: use a detached HEAD to bisect

[git.git] / git-bisect.sh

diff --git a/git-bisect.sh b/git-bisect.sh
index 57168b0ae43b07ec3c412e0c5bc19307a0770d95..4bcbaceb8bd6a5dc9021b2525f43ae5317a7d46a 100755 (executable)
--- a/git-bisect.sh
+++ b/git-bisect.sh
@@ -63,40 +63,40 @@ bisect_autostart() {
 
 bisect_start() {
        #
-       # Verify HEAD. If we were bisecting before this, reset to the
-       # top-of-line master first!
+       # Verify HEAD.
        #
        head=$(GIT_DIR="$GIT_DIR" git symbolic-ref -q HEAD) ||
        head=$(GIT_DIR="$GIT_DIR" git rev-parse --verify HEAD) ||
        die "Bad HEAD - I need a HEAD"
+
        #
-       # Check that we either already have BISECT_START, or that the
-       # branches bisect, new-bisect don't exist, to not override them.
+       # Check if we are bisecting.
        #
-       test -s "$GIT_DIR/BISECT_START" ||
-               if git show-ref --verify -q refs/heads/bisect ||
-                   git show-ref --verify -q refs/heads/new-bisect; then
-                       die 'The branches "bisect" and "new-bisect" must not exist.'
-               fi
        start_head=''
-       case "$head" in
-       refs/heads/bisect)
+       if test -s "$GIT_DIR/BISECT_START"
+       then
+               # Reset to the rev from where we started.
                start_head=$(cat "$GIT_DIR/BISECT_START")
                git checkout "$start_head" || exit
-               ;;
-       refs/heads/*|$_x40)
-               # This error message should only be triggered by cogito usage,
-               # and cogito users should understand it relates to cg-seek.
-               [ -s "$GIT_DIR/head-name" ] && die "won't bisect on seeked tree"
-               start_head="${head#refs/heads/}"
-               ;;
-       *)
-               die "Bad HEAD - strange symbolic ref"
-               ;;
-       esac
+       else
+               # Get rev from where we start.
+               case "$head" in
+               refs/heads/*|$_x40)
+                       # This error message should only be triggered by
+                       # cogito usage, and cogito users should understand
+                       # it relates to cg-seek.
+                       [ -s "$GIT_DIR/head-name" ] &&
+                               die "won't bisect on seeked tree"
+                       start_head="${head#refs/heads/}"
+                       ;;
+               *)
+                       die "Bad HEAD - strange symbolic ref"
+                       ;;
+               esac
+       fi
 
        #
-       # Get rid of any old bisect state
+       # Get rid of any old bisect state.
        #
        bisect_clean_state
 
@@ -118,7 +118,7 @@ bisect_start() {
                break
                ;;
            *)
-               rev=$(git rev-parse --verify "$arg^{commit}" 2>/dev/null) || {
+               rev=$(git rev-parse -q --verify "$arg^{commit}") || {
                    test $has_double_dash -eq 1 &&
                        die "'$arg' does not appear to be a valid revision"
                    break
@@ -366,9 +366,7 @@ bisect_next() {
        exit_if_skipped_commits "$bisect_rev"
 
        echo "Bisecting: $bisect_nr revisions left to test after this"
-       git branch -D new-bisect 2> /dev/null
-       git checkout -q -b new-bisect "$bisect_rev" || exit
-       git branch -M new-bisect bisect
+       git checkout -q "$bisect_rev" || exit
        git show-branch "$bisect_rev"
 }
 
@@ -415,7 +413,7 @@ bisect_reset() {
 
 bisect_clean_state() {
        # There may be some refs packed during bisection.
-       git for-each-ref --format='%(refname) %(objectname)' refs/bisect/\* refs/heads/bisect |
+       git for-each-ref --format='%(refname) %(objectname)' refs/bisect/\* |
        while read ref hash
        do
                git update-ref -d $ref $hash